For adiabatic process, the first law of thermodynamics is:

Explanation

An adiabatic process is one in which no heat is gained or lost by the system. The first law of thermodynamics with Q=0 shows that all the change in internal energy is in the form of work done. This condition can be used to derive the expression for the work done during an adiabatic process. When a gas expands, it does work on the surroundings; compression of a gas to a smaller volume similarly requires that the surroundings perform work on the gas. If the gas is thermally isolated from the surroundings, then the process is said to occur adiabatically. The first law is; ΔQ=ΔU+w In an adiabatic change, q = 0, so the First Law becomes 0=ΔU+w -ΔU=w or ΔU=-w Since the temperature of the gas changes with its internal energy, it follows that adiabatic compression of a gas will cause it to warm up, while adiabatic expansion will result in cooling.